The present invention relates to a new and distinct cultivar of Barberry plant, botanically known as Berberis thunbergii and hereinafter referred to by the name ‘UCONNBTB039’.
The new Barberry plant is a product of a planned breeding program conducted in Storrs, Conn. The new Barberry plant was developed by exposing pre-germinated seed to the mitotic inhibitor colchicine to create an autotetraploid plant. Specific methods used followed those published in Lehrer, J. M., M. H. Brand, J. D. Lubell, “Induction of tetraploidy in meristematically active seeds of Japanese barberry (Berberis thunbergii var. atropurpurea) through exposure to colchicine and oryzalin”, Scientia Horticulturae 119:67-71 (2008). Briefly, seeds were cold stratified for 4-6 weeks and then pre-germinated seeds with 5-7 mm of radicle emergence were exposed to a 0.1% colchicine solution for 24 hours. The maternal parent plant that provided the seed is Berberis thunbergii var. atropurpurea. Berberis thunbergii var. atropurpurea, which is not patented, and has been used in the nursery industry since the mid-1920's. The paternal parent is unknown since the seed used was open pollinated. Treated seeds were then planted in flats and grown in a greenhouse until they were large enough for ploidy analysis by flow cytometry. Seedlings that were tetraploids were grown on for further evaluation. Tetraploidy was confirmed multiple times by flow cytometry when plants were in containers and the field.
One hundred tetraploid plants were created in early 2005 and grown in a greenhouse and coldframe for their first growing season. Tetraploid plants were grown outdoors in containers during 2006 to 2010 and were evaluated for horticultural traits and fruit and seed production. In spring 2011, tetraploid plants were planted in the field for long term evaluation. Diploid Berberis thunbergii var. atropurpurea plants were grown in the same planting as tetraploid plants to serve as control plants. During the growing seasons of 2012, 2013, and 2014, tetraploid plants established in the field were evaluated for fruit production, seed production, seed germination and seedling ploidy in comparison to diploid control plants. Berberis thunbergii ‘UCONNBTB039’ was selected from among 100 tetraploid seedlings based on lack of seed production, vigorous growth, compact habit, and spreading form.
Asexual reproduction of Berberis thunbergii ‘UCONNBTB039’ by softwood stem cuttings (since 2012) made in late June through early July in a greenhouse or container nursery environment has shown that the unique features of this new barberry plant are stable and reproduced true-to-type in successive generations of asexual reproduction.